Hi, Had a similar problem. I inserted CD cartridge and got message "no discs" and then couldn't eject cartridge with CD's in. This is what I did:
Checked the fuse under bonnet (see manual) mine was OK. Then resorted to removing unit from car boot. There are 2 screws that secure, one bottom left and other bottom right. CD unit then slides out. This reveals a fuse located on the rear of the unit. Checked fuse (also OK). Next resorted to taking the thing apart.
Remove 2 screws securing fuse on back. Remove 2 small screws in the centre of the right hand side and same on left hand side, remove 3 screws at rear on the bottom - this enables you to lift the lid up gently and slide to the rear and it lifts off. If you look carefully under the CD cartridge you can see a short metal rod at an angle - if you push this gently with a screwdriver it will eject the CD cartridge (if it does not eject with gentle pressure you are pushing the wrong part, it doesn't need any excessive force). I then found that I had somehow got 7 CD's into the 6 slots. After careful re-assembly and refitting back into the car I then re-inserted CD cartridge with ONLY 6 CD's and all worked fine. If I managed to get 7 CD's in without realising it, as it didn't take any force, then I am sure that plenty of other people can accidentally do so as well.
I am not an electronics expert and so this is not as complicated as you may think - just think logically about removing the lid and don't force anything on the inside or damage any of the plastic parts.
I hope this works for you?
Chris, May 2009